Composite offset printing plate

ABSTRACT

A composite printing plate for application to the plate cylinder of an offset printing press comprised of a base plate and frame strips secured to the top surface of the base plate providing a plurality of framed openings for the reception of respective single page or other page segment sized lithographic printing plates, each printing plate being sized and shaped to be received within the confines of its respective framed opening and to be removably attached to the top surface of the base plate by adhesive means in such a manner so as to be removable from the base plate, while said base plate is fixed to the plate cylinder, for replacement by a newly prepared lithographic printing plate.

United States Patent Morton COMPOSITE OFFSET PRINTING PLATE [72] Inventor: Jay Morton, 3301 N. E. 5th

Avenue, Miami, Fla. 33137 [22] Filed: Jan. 22, 1971 [21] Appl. No.: 108,916

[52] US. Cl. ..l0l/4l5.l, 101/142, 101/453,

l0l/DIG. 12

[51] Int. Cl. ..B4lf l/28 [58] Field of Search.....10l/l30, 415.1, DIG. 12, 369

[56] References Cited UNITED STATES PATENTS 2,556,144 6/1951 Newman ..l0l/451 2,694,975 11/1954 Garver ..101/DIG. 12

2,304,787 12/1942 Avery ..l01/227X 3,016,009 1/1962 Tobey ..l01/228 FOREIGN PATENTS OR APPLICATIONS 323,933 10/1957 Switzerland ..l0l/4l5.l

Primary Examiner-Clyde I. Coughenour Attorney-John Cyril Malloy [57] ABSTRACT A composite printing plate for application to the plate cylinder of an offset printing press comprised of a base plate and frame strips secured to the top surface of the base plate providing a plurality of framed openings for the reception of respective single page or other page segment sized lithographic printing plates, each printing plate being sized and shaped to be received within the confines of its respective framed opening and to be removably attached to the top surface of the base plate by adhesive means in such a manner so as to be removable from the base plate, while said base plate is fixed to the plate cylinder, for replacement by a newly prepared lithographic printing plate.

1 Claim, 6 Drawing Figures PATENTEDUBI 10 I972 3 696, 745

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PATENTED 10 I972 3.6 96 745 SHEETEUFZ Z W F W Z a )2 I i 54 Ravi) i p; I I 51 1 (I W 1, km MI: ,nM h mlw NIH l 4 1m, 1! T553555 H q g m In} 36 48 i f i I III!!!" [MIN A I N VE N TOR J14) M01? 70/11 HTTOR'AJEX COMPOSITE OFFSET PRINTING PLATE BACKGROUND OF THE INVENTION Offset printing is the newest and fastest growing of the three major printing processes and provides a process of printing from a plane or flat surface, one which is neither raised nor depressed. The printing plates are comprised of non-printing areas which are receptive to water 'and are first dampened rendering these areas nonreceptive to ink when the ink is applied to the plate, and printing areas which are nonreceptive to water but which are readily receptive to the ink. In an offset printing press, the plate is fixed around a plate cylinder in kissing contact with a rubber blanket on a blanket cylinder, the ink from the printing areas of the plate is first offset from the plate to the blanket, then from the blanket to the paper which passes between the blanket cylinder and an impression cylinder.

For printing on both sides of the paper, upper and lower units are provided, each consisting of a plate cylinder and a blanket cylinder. No impression cylinders are used as the paper passes between the two blanket cylinders and the printing is offset from the blankets to both sides of the paper, each blanket cylinder acts as an impression cylinder for its opposed unit.

Appropriate inking and dampening systems are associated with each plate cylinder and single and multiple color printing may be produced.

STATEOF THE PRIOR ART The printing plates in general use on offset presses at present vary greatly in size but, in general and especially for big printing operations such as the printing of newspapers, magazines etc., the plates are quite large as each plate, for instance, may be sized to print one side of two newspaper pages, one side of four tabloid pages or one side of eight magazine pages. When it becomes necessary to correct an error on one page, or, for example, to make changes for various editions of a newspaper or for regional advertising, a new plate must be prepared containing two, four or eight pages of printing even though the change or correction may be to one page only.

It is necessary to shut the press down, each time a change is necessary, remove the printing plate from the plate cylinder, install the new plate in proper registration and often to make trial runs. This becomes quite costly in time lost by the press operators and in waste of paper.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a composite printing plate composed of a main base plate and frame means fixed as by adhesive to the top surface of said base plate providing a plurality of framed openings against the base plate and a plurality of conventionally prepared lithographic printing plates, each representing one page or a segment of a page of printed material, for insertion into respective framed opening on the base plate. In this manner, any one or more of the two, four or eight individual plates may be individually applied to or removed from a single composite, printing plate while it is fixed in place on the plate cylinder without disturbing the basic registration of the base plate and, as each individual plate is secured in place in its respective framed opening against the base plate by pressure sensitive adhesive, rapid replacements can be made with no problem of reregistering the printing plate thereby eliminating the necessity of trial runs.

FIG. 1 is a schematic illustration of two web offset printing press sections of a type utilizing the printing plate of the present invention;

FIG. 2 is a perspective view of a plate cylinder and a blanket cylinder forming one unit for printing on one side of the paper being fed therethrough;

FIG. 3 is a plan view of the composite printing plate assembly of the present invention;

FIG. 4 is a cross sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a greatly enlarged view of the portion 5--5 of FIG. 4;

. FIG. 6 is a back view of one printing plate illustrating the backing sheet being removed therefrom to expose the pressure sensitive adhesive on the plate.

With reference to the drawings and particularly to FIG. 1, one type of offset printing press 10 is schematically illustrated which provides opposed pairs of plate cylinders 12 and 14, and blanket cylinders 16 and 18 with continuous paper webs 20 passing between the blanket cylinders whereby the paper web is printedon both sides in the conventional manner. It should be noted, however, that the offset type of composite printing plate 22 of the present invention as illustrated mounted on a plate cylinder in FIG. 2 and unmounted in plan in FIG. 3 is applicable to all types and sizes of offset presses. For instance, some offset presses are sheet fed and some print only on one side of the paper in which case the lower blanket roller 14 is replaced by an impression roller. The composite plate 22 is also applicable to all types of single and multi-color work.

The inking and dampening systems for each unit illustrated in FIG. 1 are not shown as they may be of any conventional design whereby the composite plate 22 first contacts the dampeners which wet only the nonprinting areas, said areas thereby repelling ink when the inkers are contacted resulting in ink being applied only to the desired printing areas. The inked image is then transferred to the rubber blankets 24 of the blanket cylinders 16 and 18 from the plates 22 on the plate cylinders 12 and 14. From the blankets, 24 the inked images are transferred to the paper 20 being fed therethrough whether it be in sheet or web form.

The offset printing method just described is conventional with the plates now in general use as well as with the composite plate 22 of the present invention. The principal function of the composite plate 22 as best illustrated in FIGS. 3, 4 and 5 is to provide for a very rapid change of any one or more sections thereof for the purpose of providing any desired corrections or changes in the printed matter for any reason whatsoever with a minimal down time of the press.

In the printing of large daily newspapers, for instance, there are generally always various changes to be made for each edition of the newspaper as well as for regional advertising. In all types of newspapers, magazines and other periodicals it is also frequently necessary to make changes, corrections, etc. for one reason or another and as presses used in such printing operations utilize one piece printing plates which may, for instance, print two newspaper sheets, four tabloid sheets,-or eight magazine sheets, it becomes necessary to prepare an entire new lithographic printing plate even if the correction or change is confined to one sheet of printed matter.

When such a correction or change is necessitated the entire press operations must be shut down and the one piece printing plate removed from the plate cylinder and a new plate installed thereon in registry with the balance of the sheets being printed in that operation. This requires trial runs which waste paper as well as a considerable monetary loss due to the idling of the pressmen during the changeover.

FIGS. 2 through 5 illustrate the composite plate of the present invention and shows, by way of example only, a base plate 28 having four separate printing plates 30, 32, 34 and 36 removably affixed thereto. The number and size of sheets or segments is variable and in accordance with the type of printing operation being performed.

A frame assembly indicated generally at 40 is fixed to the top surface 38 of the base plate 28and provides generally parallel top and bottom strips 42 and 44, similar parallel side strips 46 and 48 and a pair of intersecting strips 50 and 52 disposed generally at right angles to each other and extendingrespectively along the major and minor axes of the base plate 28, connecting between the side strips 46 and 48, and the top and bottom strips 42 and 44.

The frame 40 thusly provided, forms four tabloid sized framed openings54, 56, 58 and 60 conforming exactly to the size and shape of the respective printing plates 30, 32, 34 and 36 which are received within the confines of said openings. As illustrated in FIGS. 2 and 4, the top surface 38 of the base plate 28 is provided with an adhesive 62 preferably of the pressure sensitive type and the'back surface of each printing plate 30, 32, 34 and 36 is similarly coated with adhesive 64 whereby the printing plates are firmly secured within the confines of their respective framed openings 54, 56, 58 and 60. The frame strips are adhesively, bonded, or otherwise suitably attached to the backing plate in the same manner. As illustrated in FIG. 6 each printing plate is provided with a backing cover 65 over the adhesive 64, which is left in place during the conventional preparation of the plate, to be removed only when the plate is ready to be inserted in place in its framed opening on top of the base plate 28.

As illustrated in FIGS. 4 and 5 the sum of the thicknesses of the base plate and each printing plate is equal to the sum of the thicknesses of the base plate and any of the various frame strips. If there is any variation, the thickness of the base plate and any of the frame strips would be slightly less than the thickness of the base plate and any of the printing plates.

As best illustrated in FIG. 5, all of the abutting edges of the frame strips and-printing plates are preferably rounded or bevelled as at 68 to prevent any build up of ink as would otherwise occur in a sharp slot, resulting used to print eight magazine size sheets an additional pair of frame strips would be utilized in a parallel relationship to the minor axis strip 52 with one strip disposed on each side thereof and spaced therefrom so as to provide eight equally sized framed openingsfor the reception of eight magazine size printing plates.

As previously stated there are many different size offset type printing presses using plates of various lengths and widths, and the thickness of the plates is also variable for different presses, however, the thicknesses are all measured in thousandths of an inch. In general, the composite printing plate of the present invention would be provided with a substantially equally thick base plate 28 and printing plate 30 and thesethicknesses would be variable to provide an overall thickness in which the sum of the base plate 28 and the printing plate 30 would be equal to the thickness of the printing plate required by any given printing press.

The composite plate of the present invention may be constructed of any of the materials conventionally used in printing plates of this type, for example, it may have a plastic backing plate and aluminum printing plates.

The process involved in preparing the printing plates is not described herein for it is accomplished in the manner conventional to the offset-lithography printing process. The backing plate is prepared with a suitable frame assembly in accordance with the size and number of sheets to be printed, individual printing plates are fixed in place in their respective framed openings when the composite plate is applied to the plate cylinder 12 and fixed thereon in any conventional manner, for example, by inserting the ends in a locked relation in a slot 70 as schematically illustrated in FIG. 1. The composite plates applied to all of the plate cylinders on a press are initially registered in the usual manner. In other words, the original setting-up of the press is quite conventional, however, all subsequent changes and corrections, for instance, for later editions of a newspaper or for regional advertising, new plates incorporating the desired changes or corrections are prepared in advance in the form of single sheet printing plates which may be quickly substituted for any single sheet plates which must be replaced.

When the time arrives to make the desired changes or corrections, the press is shut down for a short time, and the single sheet printing plate or plates to be replaced are peeled off of the base plates 28 in the manner illustrated in FIG. 2 and the changed or corrected plates are substituted for them by removing the backing sheet 65 and by inserting each substitute printing plate within the confines of the appropriate framed opening, the change being accomplished without removing the backing plate from the plate cylinder.

In this manner, the proper registration of the sheet or sheets are insured because the positioning of the base plates remain undisturbed on the plate cylinders and the press is ready for operation in a very minimal period of time without trial runs for checking registration. A very substantial monetary savings is therefore provided by the greatly reduced number of man hours lost by the press operators during the down time and by the elimination of wasted paper in trial runs. In large printing operations, the down time and paper waste becomes a very substantial loss over a period of time.

While the present invention is illustrated and described in a preferred form, various modifications and changes may be made therein within the scope of the appended claims.

What is claimed is:

l. A composite commercial printing plate for attachment to the plate cylinder of an offset printing press for applying a page of printed matter to one side of a paper passing through the press comprising,

a. a thin base plate of rigid curvable material having upper and lower surfaces, and an area of a size greater than two of the pages;

b. frame means including attachment means whereby said frame means is fixed to said upper surface, said frame defining at least two equally sized and shaped page size frame openings in side-by-side relation;

c. an individual page size printing plate for each of said openings, each plate being sized and shaped for reception within the confines of one of said framed openings;

d. attachment means whereby said individual printing plates for a page are removably attached to said upper surface within said confines and are adapted to be replaced by another page sized printing plate;

e. each of said individual printing plates comprising a lithograph printing plate containing water receptive non-printing areas and ink receptive printing areas and said composite printing plate is adapted to be fixed about the cylindrical face of the plate cylinder with said lower surface lying thereagainst and all of said individual printing plates being exposed for dampening and inking, and transfer of the ink from the printing areas to the paper in accordance with the lithographic offset printing process; and

f. the printing plates having an outer peripheral edge and each of said frame openings having an inner peripheral edge in substantial abutment with said outer peripheral edge of said individual printing plates fixed therein which edges are rounded to merge and blend with the exposed surface defining a channel between the printing plates and the frame for accumulating moisture and fountain fluid to repel ink from accumulating therealong and avoid printing of a borderline about reproductions from the replaceable page plates. 

1. A composite commercial printing plate for attachment to the plate cylinder of an offset printing press for applying a page of printed matter to one side of a paper passing through the press comprising, a. a thin base plate of rigid curvable material having upper and lower surfaces, and an area of a size greater than two of the pages; b. frame means including attachment means whereby said frame means is fixed to said upper surface, said frame defining at least two equally sized and shaped page size frame openings in side-by-side relation; c. an individual page size printing plate for each of said openings, each plate being sized and shaped for reception within the confines of one of said framed openings; d. attachment means whereby said individual printing plates for a page are removably attached to said upper surface within said confines and are adapted to be replaced by another page sized printing plate; e. each of said individual printing plates comprising a lithograph printing plate containing water receptive nonprinting areas and ink receptive printing areas and said composite printing plate is adapted to be fixed about the cylindrical face of the plate cylinder with saiD lower surface lying thereagainst and all of said individual printing plates being exposed for dampening and inking, and transfer of the ink from the printing areas to the paper in accordance with the lithographic offset printing process; and f. the printing plates having an outer peripheral edge and each of said frame openings having an inner peripheral edge in substantial abutment with said outer peripheral edge of said individual printing plates fixed therein which edges are rounded to merge and blend with the exposed surface defining a channel between the printing plates and the frame for accumulating moisture and fountain fluid to repel ink from accumulating therealong and avoid printing of a borderline about reproductions from the replaceable page plates. 